MY SONS SWITCH BARREL AK BUILD IDEAS

Im starting a build for my son and he got a box of AK parts and barrels and stuff for Xmas. it will be a 243 0r 260 remington loaded to light pressure.
Its going to be a light weight sporter and I want it as light as i can make it besides the heavy m70 trunion. this will be a outside the box build over the next year were he helps build it. He is 9 and will be able to shoot deer next season. I plan on letting him do as much on it as he can including some of the machine work that way he will know whats going on and how it all works and get some Shop time with Dad. It will have gas shut off as well and he will be shooting this as a non semi auto at first. Baby steps here.

Hes pretty sharp and noticed I had three barrels in the box, a 243, Win 260 Remington and 308 WIn there all model 700 take offs. he asked why there were three barels and I told him we were only going to use one but I hadent decided what one and that id keep the other two. Well hes not one to give stuff back that he just got, so he says way not use them all and just change them.

I have thought of several differant switch barrel assembly set up's in the past but they all required seperate trunions on a screw build. So got to thinking about a threaded barrel set up.

it looks like a 1"-12 thread can be used on the 23mm trunion if the bore is opend up to .9219"
that is .016 more than the factory bore. thats not much metal to get things right with with the boring bar if it dont cut good on the first try. the Yugo bore is not interupted like other trunions were there are hollow spots between the barrel and the trunion. aside from the barrel pin there is no interuptions. I really wish I had a virgin trunion to work with. the RSB will need to be removable or able to slide forward or you will not be able to unscrew the barrel. I was thinking of useing a barrel nut like the savage bolt actions and all barrels will need to be timed but that should not be a issue as once there head spaced correctly they will always be reinstalled in the same place every time.

I have seen were a guy threaded a 410 Saiga in conversion to a 500 S&W so I know it can be done. I think the model 70 Win uses a 1" thread .

this build is going to have a custom Aluminum RSB and likely a GB so I a dont have to worry about traditional looks in fact the less it looks like a AK the better for this build. people get nervious with kids shooting AK,s for some reason LOL.

I was even thinking with a differant bolt I could even do a 410 SG barrel for it.

I was actually thinking of a custom RSB/optics rail that would stay with the trunion and then I could keep a chart of what scope settings work with what barrel and then I would not need to sight it in every time. or if a side rail is used ( somthing Im not a big fan of ) I would just need a gastube dust cover mount holder like on a Saiga 410.

there are a bunch of ways mount a RSB . the barrel pin holes will not be used so they could be tapped to hold a GB or it could be sanwitched enbetween the barrel and trunion and then also held with screws so it retains zero during barrel changes. I have a few L1AI Gb,s so I could use them on all the barrels but the super heavy varmint set up were to Od will need to be bigger and there are heavy barrel L1A1 block avaliable. Im starting to like this idea more and more. I could go from a 16" barrel super light weight carry deer rifle to a 28" 1" no taper barrel 260 rem 1000 yard varmint set up in minutes.

Im actualy now staring at my Sagia 308 and thinking what if????? and then I could shoot 61,000 PSI loads. maybe even 300 WSM loaded down slightly to keep the pressures in line.

whats the inside of a 308 Saiga trunion look like?? is there cavitys or is it uninterupted???? Judging by the rivet placement Im guessing its got cavitys

how ever there was the 410 Saiga conversion to 500S&W that got threaded. HMMMMMMM

You could toss the RSB and use a Galil or Valmet gas tube. You'll have to file the ears on the Yugo trunnion to accept the dovetails.

Most Valmets and all Galils used top cover mounted sights. A few Valmets had the rear sights on the back of the gas tube, more or less in the same position as with a conventional RSB.

With my Yugo trunnion, it looks like a 15/16-12 tap might work. I found them from a couple of places online for $35 or so.

There are some pictures around of a switchbarrel AK using an Uzi barrel nut and flanged barrel setup. You could turn the threads onto a bushing, press it into the receiver, and anchor it with the stock Yugo pin. You might have to clearance the pin if it hangs through into the ID. With the Uzi setup, you could then just slip the barrel in and tighten the nut, no separate headspacing step needed.

If you're not working with a blank where you could cut the flange to start with, you could machine a collar, heat it, and slide it up to go into a .003" or so groove in the barrel, where it would lock in place.

I was going to mention interrupted threads as a good idea. Should work well, although you may have to use some acme-style threads to get good interface. Something thick.

Another idea may be more simple than you expect - do you know how the PKM barrel locks? It has a standard style trunion that is fairly long, perhaps 4" long. The barrel slips into position and a "wedge" locks it in place. The wedge is set on a cross-ways dovetail. You're supposed to use a bullet tip to slide it sideways, but if you were to add a hinged or curved handle of some sort on the side, you could set it so that the handle pries it sideways. Kind of like a prybar or crowbar. Something to pull the wedge loose after the barrel heats up. The headspace is set and THEN the notch for the locking wedge is cut into the barrel.

Following this idea, you could use the barrel pin hole as a starting point for a wedge. Maybe square out the hole so the barrel is notched with a larger area than just using the hole as-is.

I think Ilya's picture gallery has some of the PKM pics you should look at.

well I did some investigating and remington 700 barrels use a 1 1/16 -16 thread that means a trunion bore of almost exactly 1" depending on thread engagemwnt and tightness. so 23 mm trunion would need be opened up about .095" that would give some wiggle room on getting a cutter on a boring bar dialed in ferfect before a final cut. there is pleanty of meat arond the bore on a yugo trunion.

I like the idea of retaining the remington thread size at most barrels that are cheap take offs are remington. the threads are to short unfortunatly but the good news is that they can be used to start a tap straight if one should decide to not use a lathe to cut them.

there are special taps and dies avalaible for about $50 each. brownells has them also but there more. i havent serched every were yet. there are other threads that might be closer small ring mauser uses a 1.10"-12 thread that requires 1.018 hole.

I have a Howa barrel here and th threads are odd the od is around 1.020 but it looks like it would be pretty close to a 23mm hole to be threaded. ruger M77 is close also but might be to small around .995 od not sure what the TPI is but i thing its 16 but .925 would be the needed bore for it so 23mm is .020 to small it looks like. dammm

You could toss the RSB and use a Galil or Valmet gas tube. You'll have to file the ears on the Yugo trunnion to accept the dovetails.

were are these avalibale at?? any one got a picture?? this sounds iseal to keep the weight down. he can barely hold up a 22lr bolt action right now so I really need to cut some weight and hope he grows in the next year.

To determine the proper drill size for 75% thread on a special pitch tap use the following formula:
Drill Size = Major Diameter - (.975 divided by the number of threads per inch).
For example, with a 1/4-32 tap, .250" - .0305 = .2195 (7/32" or #2 drill size).